This invention is concerned with flooding of underground formations, such as oil-bearing strata and the like, and is more particularly concerned with an improved pump installation for pumping sub-surface water to an oil-bearing formation, and with improved control valve apparatus.
In the secondary recovery of fluid hydrocarbons, such as oil, it is common practice to flood the hydrocarbon-bearing formation with water pumped through a bore hole, thereby applying fluid pressure which increases the yield of the desired hydrocarbon from its underground formation. Both surface water and sub-surface water have been employed for this purpose. In the employment of sub-surface water, two schemes have been utilized -- (1) pumping the water upwardly to the surface through a first bore hole, then downwardly to the hydrocarbon-bearing formation through a second bore hole, and (2) pumping the water through a single bore hole communicating with both the water-bearing zone and the hydrocarbon-bearing zone. As will appear more fully hereinafter, the present invention is principally concerned with the second technique.
The following patents are typical of the prior art dealing with flooding oil-bearing strata and the like: Krueger; U.S. Pat. No. 2,808,111 Van Den Beemt; U.S. Pat. No. 2,706,526 Gray et al; U.S. Pat. No. 2,551,434 Heath; U.S. Pat. No. 2,347,779 Arutunoff; U.S. Pat. No. 3,170,520 Engle; U.S. Pat. No. 3,354,952 Hassler; U.S. Pat. No. 2,352,834 Chenoweth; U.S. Pat. No. 3,455,382.
Krueger, Van Den Beemt, and Gray et al pump water downwardly through a bore hole and through a packer to flood an oil-bearing zone communicating with the bore hole at a lower level. Heath employs a similar technique, but in which the water pressure is high enough to avoid the need for a pump. The flow rate is regulated by a mechanically adjusted valve. Arutunoff and Engle pump upwardly through a bore hole for flooding. Hassler and Chenoweth are broadly concerned with regulation of the flow of the flooding medium.
As will appear more fully hereinafter, underlying the present invention is the discovery of the need for a critical type of flow control, by means of a special flow control valve in conjunction with a submergible pump. Valves of various types in wells and/or in conjunction with pumps have of course been known for many years. See, for example, the following prior patents: O'Rourke, U.S. Pat. No. 3,807,894; Miller, U.S. Pat. No. 3,084,898; Page, U.S. Pat. No. 3,477,507; Baker, U.S. Pat. No. 1,631,509; Garrett, U.S. Pat. No. 3,698,411; Litchfield et al, U.S. Pat. No. 3,698,426; Vincent, U.S. Pat. No. 3,294,174; Pistole et al, U.S. Pat. No. 3,007,524; Bows, U.S. Pat. No. 3,747,618; Verheul, U.S. Pat. No. 3,640,303; Reaves, U.S. Pat. No. 3,610,569; Kruse et al, U.S. Pat. No. 1,829,704; Natho, U.S. Pat. Re. No. 25,109; and Canadian Pat. No. 749,740. However, the prior art is devoid of a teaching of the type of pump discharge flow control in flooding or the type of flow control valve required by the invention.